Extracts of bone tissues are being investigated in order to identify bone specific proteins and to characterize their structure and biological function. A heat labile, trypsin sensitive protein (Mr congruent to approximately equal 65,000) with chemotactic activity for 'osteoblast-like' cells has been identified and partially purified from guanidine extracts of demineralized rat bone matrix powder and from guanidine EDTA etracts of both embryonic human bone and rqt calvaria. Future studies will include the examination of cementum proteins and the isolation of cementoblasts in order to understand the mechanisms regulating periodontal ligament-cementum attachment interations. Studies will also continue on the purification and biological function of the bone chemotactic protein.